drop leech hook in test scheduler

The explicit flush was clearing undo history, and the hook will need
re-working to support propagating OpChanges correctly. It will likely
come back as a GUI hook, instead of one in pylib.

pylib/anki/scheduler/v3.py

@@ -14,7 +14,6 @@ from __future__ import annotations
 from typing import Tuple, Union
 
 import anki._backend.backend_pb2 as _pb
-from anki import hooks
 from anki.cards import Card
 from anki.consts import *
 from anki.scheduler.base import CongratsInfo
@@ -23,6 +22,7 @@ from anki.types import assert_exhaustive
 from anki.utils import intTime
 
 QueuedCards = _pb.GetQueuedCardsOut.QueuedCards
+SchedulingState = _pb.SchedulingState
 
 
 class Scheduler(SchedulerBaseWithLegacy):
@@ -101,9 +101,7 @@ class Scheduler(SchedulerBaseWithLegacy):
         assert 1 <= ease <= 4
         assert 0 <= card.queue <= 4
 
-        new_state = self._answerCard(card, ease)
-
-        self._handle_leech(card, new_state)
+        self._answerCard(card, ease)
 
         self.reps += 1
 
@@ -138,19 +136,9 @@ class Scheduler(SchedulerBaseWithLegacy):
 
         return new_state
 
-    def _handle_leech(self, card: Card, new_state: _pb.SchedulingState) -> bool:
-        "True if was leech."
-        if self.col._backend.state_is_leech(new_state):
-            if hooks.card_did_leech.count() > 0:
-                hooks.card_did_leech(card)
-                # leech hooks assumed that card mutations would be saved for them
-                card.mod = intTime()
-                card.usn = self.col.usn()
-                card.flush()
-
-            return True
-        else:
-            return False
+    def state_is_leech(self, new_state: SchedulingState) -> bool:
+        "True if new state marks the card as a leech."
+        return self.col._backend.state_is_leech(new_state)
 
     # Next times
     ##########################################################################

pylib/tests/test_schedv2.py

@@ -429,7 +429,8 @@ def test_reviews():
 
     hooks.card_did_leech.append(onLeech)
     col.sched.answerCard(c, 1)
-    assert hooked
+    if not is_2021():
+        assert hooked
     assert c.queue == QUEUE_TYPE_SUSPENDED
     c.load()
     assert c.queue == QUEUE_TYPE_SUSPENDED

pylib/tools/genhooks.py

@@ -18,7 +18,12 @@ from hookslib import Hook, write_file
 ######################################################################
 
 hooks = [
-    Hook(name="card_did_leech", args=["card: Card"], legacy_hook="leech"),
+    Hook(
+        name="card_did_leech",
+        args=["card: Card"],
+        legacy_hook="leech",
+        doc="Called by v1/v2 scheduler when a card is marked as a leech.",
+    ),
     Hook(name="card_odue_was_invalid"),
     Hook(name="schema_will_change", args=["proceed: bool"], return_type="bool"),
     Hook(